TWAIN not working at all?

[Pauwehla]

In XnViewMP 0.68 on Win7x64 there is
no reaction at all when clicking
File > Select TWAIN source or
File > TWAIN scan.

The menu just closes.

I am using three displays.
but the Epson Scanner V300 is working very
well with very old versions of ThumbsPlus and Photoshop
in this environment.

[xnview]

IF you have twain driver x32, you need the x32 version of XnViewMP

[cday]

If you are using XnViewMP x64 you might try installing XnViewMP x32 as well and test that -- the very old versions of ThumbsPlus and Photoshop you are using are no doubt x32.

TWAIN is confusing on x64 systems and I can't immediately offer an explanation, but both versions of XnViewMP can be installed at the same time and it would be a simple test to perform...

[Pauwehla]

Thank you very much for your help.
Your answers does explain the problem very well.
AND: The problem is solved!
Did install 32bit XnViewMP too and TWAIN32 now works with it.